Impact of Interbranch Correlation on Multichannel Spectrum Sensing With SC and SSC Diversity Combining Schemes

Multiantenna receivers are often deployed in cognitive radio systems for accurate spectrum sensing. However, correlation among signals received by multiple antennas in these receivers is often ignored which yields unrealistic results. In this paper, the effect of this correlation is accurately quantified by deriving analytical expressions for the average probability of detection. Alternative simpler expressions are also derived. These are done for selection combining (SC) and switch and stay combining (SSC) diversity techniques in dual arbitrarily correlated Nakagami-m fading channels. Then, it is repeated for triple exponentially and identically correlated Nakagami-m fading channels with SC diversity technique. Analysis results show that the interbranch correlation impacts the detector performance significantly, especially in deep fading scenarios. Also, SC outperforms SSC as expected. However, the difference between them becomes very small in low fading and highly correlated scenarios, which indicates that the simpler SSC scheme can as well be deployed in such situations.